Because people that have chronic pain issues often have issues with mental health. It tends to limit their capacity for healthy coping mechanisms such as exercise. Also you obviously have never conducted a study (or taken a statistics class, if you did you didn't learn anything) by making a post like that.

Nearly one in 10 young people are experiencing both persistent physical pain and suicidal feelings, according to a new paper from researchers from the University of Oxford, Cambridge, Oslo (Norway), King’s College London, and the Parc Sanitari Sant Joan de Deu (Spain).

For people too lazy to click the link and read the first paragraph. Its both, not just one or the other.

The article says both suicidal thoughts and physical pain.